Trust as a catalyst: how institutional and market trust interact to shape milk consumption in China

China’s dairy market has long been characterized by a structural imbalance between high production and low consumption, constraining improvements in residents’ nutritional health. Drawing on data collected from 1737 respondents through a large-scale stratified survey, this study employs an ordered logit model, supplemented by a double machine learning approach to mitigate potential omitted-variable bias, to examine the associations of institutional and market trust with residents’ milk consumption, as well as the interaction between these two forms of trust. The results indicate that both institutional trust and market trust are positively and significantly associated with milk consumption and exhibit robust complementarity. However, heterogeneity analysis shows that this complementary relationship is not statistically significant in fourth-tier cities or among households without caregiving burdens, indicating marked contextual variation in the complementarity between the two dimensions of trust. Moreover, institutional trust, market trust, and their interaction are positively and significantly associated with consumers’ willingness to try plant-based milk, highlighting trust’s relevance to ecologically sustainable dietary transitions. By introducing a framework centered on the interaction between institutional and market trust, this study advances theoretical understanding of trust in food consumption and offers micro-level evidence for context-sensitive strategies to unlock China’s dairy market potential.